A question of lifting bodies underwater

In summary, the conversation is discussing the buoyancy of two rubber coated kevlar balls - one filled with air and the other with helium - when submerged underwater. It is mentioned that the ball with helium may be harder to keep underwater due to its lighter weight. It is also noted that helium is easier to compress than air. The conversation concludes with the information that the difference in lift between the two balls is about 0.1%.
  • #1
Dr Quest
9
0
If I have two rubber coated kevlar balls, one is filled with air and the other has a gas like helium in it, if submerged underwater, would the ball with helium be harder to keep underwater than the air filled ball would be, or would they be equal in their buoyancy?
Also is helium easier to compress than air, I would imagine it would be but I don't have any schooling in this field.
Thanks for the site, and any answers to my questions.
 
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  • #2
The way the definition of buoyancy works, the buoyancy is the same - what is different is the weight of the two gas-filled spheres. Since the one filled with helium is lighter, the net force required to keep it submerged is higher.
 
  • #3
Russ_watters is right. But you cannot feel the difference. You must measure the two lifting forces with a very precise device. The difference in lift is about 0.1%.
 
  • #4
Thanks for the info!
 

1. What is a lifting body?

A lifting body is a type of aircraft or vehicle design that produces lift without the use of traditional wings. Instead, the entire body of the vehicle is shaped to generate lift, allowing for more efficient flight or movement through the air or water.

2. How do lifting bodies work underwater?

Underwater lifting bodies work by utilizing the principles of buoyancy and hydrodynamics. The shape of the body is designed to create a lower pressure area above the body and a higher pressure area below it, causing the body to rise. This allows for efficient movement through the water without the need for traditional propulsion methods.

3. What are some examples of lifting bodies used underwater?

There are many examples of lifting bodies used underwater, including submarines, underwater gliders, and hydrofoils. These vehicles all use different methods of generating lift but share the common characteristic of using their body shape to create buoyancy and move through the water.

4. What are the advantages of using lifting bodies underwater?

The use of lifting bodies underwater has several advantages, including increased efficiency and maneuverability, reduced noise levels, and the ability to operate in shallow waters. Additionally, lifting bodies are less affected by rough sea conditions, making them more reliable for operations in challenging environments.

5. What challenges are associated with lifting bodies underwater?

One of the main challenges of using lifting bodies underwater is the need for precise design and engineering. The shape and weight distribution of the body must be carefully considered to ensure optimal lift and stability. Additionally, lifting bodies may be more susceptible to instabilities such as yaw, pitch, and roll, which can impact their performance and safety.

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